1. Technical Field
The present invention relates to a battery module and a method of manufacturing the same and, more particularly, to a battery module having a gas ventilation outlet and a method of manufacturing the same by which safety can be guaranteed.
2. Related Art
A battery module includes a few or several tens of rechargeable batteries connected to each other. The rechargeable battery can be repeatedly charged and discharged because its chemical and electrical energy conversion is reversible.
These days, more and more mobile wireless electronic products are being developed, and the requirement for rechargeable batteries to have a high energy density has increased as the size thereof has been minimized and the weight reduced.
Widely used batteries include a nickel-cadmium battery, a nickel-hydrogen battery, a lithium battery, and the like. Particularly, the lithium rechargeable battery has an operation voltage of 3.6 V, which is triple that of the nickel-cadmium battery or the nickel-hydrogen battery, and also has a high energy density per unit weight. Therefore, the lithium rechargeable battery is becoming rapidly popular as a power supply for mobile electronic devices. Such a lithium rechargeable battery can be classified into a lithium ion rechargeable battery, a lithium ion polymer battery, and a lithium polymer battery. The lithium polymer battery is nearly similar to the lithium ion rechargeable battery, except that electrolyte of the lithium ion rechargeable battery is replaced by polymer. This property contributes to flexibility of design in the shape as well as to higher safety.
A typical rechargeable battery includes an electrode assembly having a positive electrode, a negative electrode, and a separator interposed therebetween, a casing which provides a space for storing the electrode assembly, and a cap plate combined with the casing to seal the electrode assembly. Each of the positive and negative electrodes includes a coated portion where an activation material is coated and an uncoated portion where the activation material is not coated. The uncoated portion is provided to collect the current generated in the positive and negative electrodes, and a conductive tap is attached thereto. The conductive tap induces the current generated in the positive and negative electrodes to the positive and negative terminals, respectively. The rechargeable battery may be manufactured in a variety of shapes such as a cylindrical, rectangular, and pouch type, depending on the shapes of the electrode assembly and the casing.
The battery module having a plurality of rechargeable batteries connected to one another as described above is being widely used as a power supply for driving motors of portable miniaturized electronic devices, such as a mobile phone, a personal computer, and a camcorder, and also for hybrid electric vehicles.
The battery module also includes various safety devices in order to prevent excessive pressure or heat. For example, if the internal pressure of the battery module exceeds an allowable limit, the battery module externally ventilates its internal gas to prevent explosion. For this purpose, the battery module should be designed to safely ventilate the internal gas. If a space for circulating the internal gas does not exist in the battery module, and the internal gas cannot be safely ventilated, the internal pressure may continuously increase, and the battery module may finally explode.